To transfer files via the proFTPD server, you first need to configure FTP access rules. Follow these steps.

Open a new Linux terminal and ensure you are logged in as root.

Create a new group named ftp. This group will contain those user accounts allowed to upload files via FTP.

groupadd ftp

Add your account (in this example, susan) to the new group. Add other users if needed.

usermod -a -G ftp susan

Change the ownership and permissions of the htdocs/ subdirectory of the XAMPP installation directory (typically, /opt/lampp) so that it is writable by the the new ftp group.

cd /opt/lampp

chown root.ftp htdocs

chmod 775 htdocs

If you’re using XAMPP in a single-user scenario and there will only be one user transferring files via FTP, you can skip creating a new group and instead simply transfer full ownership of the htdocs/ directory to that user. To do this, use a command like chown susan.susan htdocs.

Ensure that proFTPD is running in the XAMPP control panel.

You can now transfer files to the XAMPP server using the steps below:

Start an FTP client and enter connection details as below.

If you’re connecting to the server from the same system, use "127.0.0.1" as the host address. If you’re connecting from a different system, use the network hostname or IP address of the XAMPP server.

Use "21" as the port.

Enter your Linux username and password as your FTP credentials.

Your FTP client should now connect to the server and enter the /opt/lampp/htdocs/ directory, which is the default Web server document root.

Transfer the file from your home directory to the server using normal FTP transfer conventions. If you’re using a graphical FTP client, you can usually drag and drop the file from one directory to the other. If you’re using a command-line FTP client, you can use the FTP PUT command.

Once the file is successfully transferred, you should be able to see it in action by browsing to http://localhost/example.php, as shown below: